Ivor Horton's Beginning Visual C++ 2012

Queue Containers

A queue<T> container implements a first-in first-out storage mechanism through an adapter. You can only add to the end of the queue or remove from the front. Here’s one way you can create a queue:

queue<string> names;

This creates a queue storing elements of type string. By default, the queue<T> adapter class uses a deque<T> container as the base, but you can specify a different sequence container as a base, as long as it supports the operations front(), back(), push_back(), and pop_front(). These four functions are used to operate the queue. Thus, a queue can be based on a list or a vector container. You specify the alternate container as a second template parameter. Here’s how you would create a queue based on a list:

queue<string, list<string>> names;

The second type parameter to the adapter template specifies the underlying sequence container that is to be used. The queue adapter class acts as a wrapper for the underlying container class and essentially restricts the range of operations you can carry out to those described in the following table.

FUNCTION	DESCRIPTION
back()	Returns a reference to the element at the back of the queue. There are two versions of the function, one returning a const reference and the other returning a non-const reference. If the queue is empty, then the value returned is undefined.
front()	Returns a reference to the element at the front of the queue. There are two versions of the function, one returning a const reference ...